1. Field of the Invention
The present invention relates to a device for realizing upstream aggregation and downstream translation of a virtual local area network (VLAN) and a method thereof, and particularly to a device and a method thereof that can realize upstream aggregation and downstream translation of a VLAN according to an ingress VLAN translation table, an egress VLAN translation table, and a filtering database stored in a buffer.
2. Description of the Prior Art
“TR156: Using GPON Access in The Context of TR-101” and “CTC EPON Equipment Technical Requirement V3.0” define virtual local area network (VLAN) N:1 upstream aggregation (VLAN N:1). In addition, VLAN 1:N downstream translation (VLAN 1: N) is reverse mapping behavior of the VLAN N:1 upstream aggregation.
The “CTC EPON Equipment Technical Requirement V3.0” defines the VLAN N:1 upstream aggregation and the VLAN 1:N downstream translation as follows: the VLAN N:1 upstream aggregation is that a plurality of upstream packets (e.g. VLAN 1, 2, . . . , X) are aggregated to an upstream translation packet (e.g. VLAN Y), and the VLAN 1:N downstream translation is that a downstream packet (e.g. VLAN Y) is reversely mapped to a plurality of downstream translation packets (e.g. VLAN 1, 2, . . . , X).
The “CTC EPON Equipment Technical Requirement V3.0” describes the VLAN N:1 upstream aggregation as follows: in the N:1 VLAN upstream aggregation, an optical line terminal (OLT) or an optical network unit (ONU) can aggregate a plurality of upstream packets to an upstream translation packet (e.g. VLAN Y). The “CTC EPON Equipment Technical Requirement V3.0” describes the 1:N VLAN downstream translation as follows: a downstream packet (e.g. VLAN Y) inputted from an internet port can be reversely mapped to a plurality of downstream translation packets (e.g. VLAN 1, 2, . . . , X).
The N:1 VLAN upstream aggregation can be realized by an ingress VLAN translation table. The ingress VLAN translation table can set an upstream packet inputted from each user port to be translated into an upstream translation packet outputted through an internet port. Therefore, the ingress VLAN translation table can set a plurality of upstream packets (e.g. VLAN 1, 2, . . . , X) inputted from the same user port or different user ports to be translated into the same upstream translation packet (e.g. VLAN Y) to realize the N:1 VLAN upstream aggregation.
The 1:N VLAN downstream translation can be realized by an egress VLAN translation table. The egress VLAN translation table can set a downstream packet (e.g. VLAN Y) inputted from each internet port to be translated into a downstream translation packet (e.g. VLAN X) outputted through a user port. Therefore, the egress VLAN translation table can set a downstream packet to be translated into a downstream translation packet on different user ports. For examples, the egress VLAN translation table sets a downstream packet (e.g. VLAN Y) to be translated into a downstream translation packet (e.g. VLAN 1) on a first user port, and sets the downstream packet (e.g. VLAN Y) to be translated into another downstream translation packet (e.g. VLAN 2) on a second user port to realize the 1:N VLAN downstream translation.
The prior art can utilize the egress VLAN translation table to realize the 1:N VLAN downstream translation to translate a downstream packet into different downstream translation packets on different user ports, but only to translate a downstream packet into the same downstream translation packet on the same user port. For example, e.g. the prior art only translates the downstream packet (VLAN Y) into the downstream translation packet (VLAN 1) on the first user port. That is to say, the prior art can not translate a downstream packet (VLAN Y) into different downstream translation packets (e.g. VLAN 1 and VLAN 2) on the same user port (e.g. the first user port).